Ink jet printing is a well-known technique by which printing is accomplished without contact between the printing device and the substrate on which the printed characters are deposited. Briefly described, ink jet printing involves the technique of projecting a stream of ink droplets to a surface and controlling the direction of the stream electronically so that the droplets are caused to form the desired printed image on that surface. This technique of noncontact printing is particularly well suited for application of Characters onto irregularly shaped surfaces, including, for example, the bottom of glass, metal, or plastic containers, used for holding cosmetic, pharmaceutical, liquor, and health care products.
Reviews of various aspects of ink jet printing can be found these publications: Kuhn et al., Scientific American, April, 1979, 162-178; and Keeling, Phys. Technol., 12(5), 196-303 (1981). Various ink jet apparatuses are described in the following U.S. Pat. Nos.: 3,060,429, 3,298,030, 3,373,437, 3,416,153, and 3,673,601.
In general, an ink jet composition must meet certain rigid requirements to be useful in ink jet printing operations. These relate to viscosity, resistivity, solubility, compatibility of components and wettability of the substrate. Further, the ink must be quick-drying and smear resistant, resist alcohol rubs, and be capable of passing through the ink jet nozzle without clogging, and permit rapid cleanup of the machine components with minimum effort.
Many of the surfaces on which ink jet printing is utilized are non-porous. The ink used for these applications must adhere well to the non-porous substrate and normally must be alcohol rub resistant. Many of the cosmetic, pharmaceutical, liquor, and health care products contain alcohols, such as isopropyl alcohol. During the manufacture and transportation of the products containing alcohol, there exists a possibility that the products may spill out of the containers and smear the printing codes.
Several ink compositions known heretofore are not suitable for the above use. For example, UK Patent Application GB 2,105,735 discloses a jet ink composition comprising an oil soluble dye-impregnated polyurethane latex dispersed in an aqueous medium.
U.S. Pat. No. 4,680,332 discloses a jet ink composition comprising a water insoluble polymer such as a polyacrylate dispersed in a liquid medium, the polymer containing therein an oil soluble dye, and a nonionic stabilizer permanently attached thereto.
U.S. Pat. No. 5,207,825 discloses a jet ink composition which comprises an aqueous liquid vehicle, a colorant, and a polymeric additive which is a substituted bisphenol A derivative.
U.S. Pat. No. 5,080,716 discloses a jet ink composition comprising a recording agent, a liquid medium capable of dissolving or dispersing the recording agent, and a substituted benzene or toluene sulfonamide compound.
U.S. Pat. No. 5,254,158 discloses an ink composition which comprises an aqueous liquid vehicle, a colorant, and an additive selected from the group consisting of amine alkoxylates, sorbitan monoester alkoxylates, alkylene oxide adducts of glycerin, and mixtures thereof.
U.S. Pat. Nos. 5,215,577 and 5,178,671 disclose jet ink compositions comprising a recording agent and a liquid medium for dissolution or dispersion thereof, the recording agent being an aromatic sulfonated diazo compound.
U.S. Pat. No. 5,131,949 discloses a jet ink composition including a recording agent, a liquid medium capable of dissolving or dispersing the recording agent, and a compound having an amide group.
U.S. Pat. No. 5,213,613 discloses a jet ink comprising a recording agent and a liquid medium capable of dissolving or dispersing the recording agent therein, wherein the ink contains an imide compound and at least one compound selected from the group consisting of urea, thiourea and derivatives thereof, and volatile alkaline compounds.
U.S. Pat. No. 4,692,188 discloses a process for the preparation of jet ink compositions, comprising (1) dissolving in a water-immiscible organic solvent a polymer composition and an organic oil soluble dye; (2) adding an aqueous phase water surfactant mixture thereto; (3) affecting emulsification thereof; and (4) subsequently evaporating from the aforementioned mixture the solvent thereby resulting in an ink with the dye trapped in the polymer particles suspended in the aqueous phase. The polymer compositions include polycarbonates, polystyrene, polymethacrylates and copolymers thereof.
U.S. patent application 08/121,296, filed Sep. 14, 1994, and assigned to the same entity as the instant application, discloses an ink composition for use in drop-on-demand ink jet operations for printing on porous substrates such as paper and card board, which has low levels of volatile organic compounds and that is both non-teratogenic and non-carcinogenic.
All of the water based jet ink compositions disclosed by the above references are generally directed to ink compositions suitable for printing on paper and are not considered suitable for printing on the containers which are non-porous. To obtain the necessary qualities of being fast drying and demonstrating good adhesion, solvent-based ink must be used. Therefore a need exists for a jet ink composition that is solvent-based, fast drying, and has good adhesion to non-porous containers and isopropyl alcohol rub resistance. The ink should be capable of being printed onto glass, plastic, and metal surfaces with good adhesion.